Talk by Machteld E. Kamminga

Probing and tuning spins in solid-state systems

By: Machteld E. Kamminga, Debye Institute for Nanomaterials Science, Utrecht University, Utrecht, The Netherlands

Abstract

Spin interactions in solid-state systems are fundamental to understanding a wide range of physical phenomena and play a critical role in determining the electronic and magnetic properties of materials. In magnetic systems, exchange interactions drive spin alignment, giving rise to magnetic behaviours observed in, for example, ferromagnets, antiferromagnets, and spin glasses.

In this talk, I will put neutron scattering forward as a suitable scientific tool to study the magnetism in these phases of matter, and I will demonstrate this by discussing our latest advances in probing and tuning the magnetism in various chemical systems.

First I will focus on structurally frustrated rare-earth antiferromagnets. Geometric frustration occurs in systems where the spatial arrangement of interacting components, in this case spins, prevents all pairwise interactions from being simultaneously satisfied. This typically arises in systems with antiferromagnetic interactions on specific lattice geometries, such as triangular, Kagome, or pyrochlore lattices. Here I will demonstrate how this leads to a complex magnetic phase diagram in a rare-earth antiferromagnet [1].

After that I will discuss the magnetic phases induced by Cr-doping Mn₃Sn. The antiferromagnet Mn₃Sn is a well-established candidate for spintronics, showing a very large anomalous Hall effect at room temperature. The origin of this effect stems from its topological nature, which in turn originates from the underlying 120° inverse-triangular antiferromagnetic structure. Here, I will present Cr-doping as a direct tool to tune the anomalous Hall effect, via distortions in the magnetic structure.

These results highlight the complex coupling between doping and anomalous Hall response, allowing for vastly tunable spintronic properties of this topological Weyl semimetal through Cr doping [2]. 

[1] P. Witte, D. Sheptyakov, E. Lhotel, N. Artrith, R. de Hoogh, G. Perversi, K. Lefmann & M.E. Kamminga,“Complex magnetic interactions in geometrically frustrated TbOF”, Chem. Mater. 2026, 38, 5760-5766.

[2] P. Maderson, Z. Cheng, R. Sibille, Y. Guo, N. Qureshi, S. Bhattacharyya, H. Jacobsen & M.E. Kamminga, in preparation. 

Host

Prof. Kim Lefmann